Life of a spring

Our counterparts have designed a spring for a valve application.
the entire component depends on the tension of the spring
We need to calculate the tension life of a spring(i.e the duration for which the tension in a spring remains a constant)
Please provide me a solution

You need to find a chart of the material the spring is made out of that graphs the fatigue life vs. the stress. If your stress falls under the curve, it will last forever. If it intercepts the curve, it will fail at N-cycles.

Astronuc can give you a better explination. Thats a question for Material Science section.

try finding books of Mechanical Design subjects, or Theory of Machines. they usually contain such answers, they are long formulas with many many variables sometimes more than 8 variables that depend on the materials and applications of the spring. good luck